Apparatus for developing electrostatic image



April 27, 1965 B. D. EISNER 3,180,313

APPARATUS FOR DEVELOPING ELECTROSTATIC IMAGE Filed Oct, 19, 1962 3Sheets-Sheet 1 I alt/0V 0. 5571/5? ucT-r mrayf 1 B. D. EISNER April 27,1965 I APPARATUS FOR DEVELOPING ELECTROSTATIC IMAGE 3 Sheets-Sheet 2 1Filed. Oct. 19, 1962 B. D. EISNER April 27, 1965 APPARATUS FORDEVELOPING ELECTROSTATIC IMAGE Filed Oct. 19, 1962 3 Sheets$heet 3 a9 ilg.

United States Patent C) 3,180,313 APPARATUS FOR DEVELOPING ELECTRO-STATIC IMAGE I Burton D. Eisner, Highland Park, Ill., assignor toAmerican Photocopy Equipment Company, Evanston, Ill., a

corporation of Illinois Filed Oct. 19, 1962, Ser. No. 231,771

. 4 Claims. (Cl. 118637) The present invention relates toelectrophotographic printing and more particularly to means forreplenishing developing powder in the developing unit of such a machine.

It is desirable in the electrophotographic printing process to use apowder or toner mix which is of fine grain. In the use of such tonermix, problems arise because the powder tends to pack or bridge thedischarge opening. Furthermore, problems occur in metering the tonerpowder, especially in small quantities.

It is an object of the present invention to provide a replenishing ordispensing unit for periodically replenishing a toner reservoir andwhich is effective to positively discharge a predetermined amount oftoner powder free of any packing or bridging of the powder in thedischarge opening. Reliable discharge is assured even though tonerpowder is employed, which is much finer than that which can beaccommodated by conventional replenishing devices.

It is a more specific object to provide a replenishing device which iscapable of actually metering out predetermined quantities of powder inorder to keep the reservoir up to rated level and in which the amount ofpowder, which is discharged at each operation may be actually adjusted.over a wide range.

It is an overall object of the present invention to provide areplenishing unit which can be easily adapted for use in any of theseveral different types of electrophotographic printing machines andwhich is economical to manufacture and easy to maintain.

Other objects and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings in which:

FIGURE 1 is a simplified vertical fragmentary section of a photocopymachine employing the present invention;

FIG. 2 is a schematic diagram of the portion of the control circuit forthe replenishing unit;

FIG. 3 is a plan view, in partial section, of the developing unit whichreceives the toner from the replenishing unit;

FIG. 4 is a vertical-section taken along ;-4 in FIG. 3 through thereplenishing unit constructed in accordance with. the present invention;

FIG. 5 is an exploded view of the dispensing or replenishing elements;and v. 7

FIG. 6 is a fragmentary section showing adjustment of the choke plate tovary the discharge of the replenisher.

While the invention has been described in connection with a preferredembodiment, it will beunderstood that it is not intended to limit theinvention to the particular embodiment shown but it is, on the contrary,intendedice in copending application, Serial No. 211,779, filed July 23,1962. All that need be related for understanding of the presentinvention is that copy sheet 13, when it enters the developing unit, hasan electric charge image established on it corresponding to theoriginal.

In the developing unit 11 a bin 16 is provided for holding the toner mixso that a developing cylinder 17 can pick up the mix and brush it on thecopy sheet 13. The toner will stick to the parts of the copy sheet whichhave an electric charge and thereby visually display the image on thecopy sheet corresponding to the original. The full explanation of thedeveloper cylinder 17 and the manner in which the toner mix is picked upand applied to the copy sheet is set forth in detail in theaboveidentified copending application. For present purposes, is sufiicesto explain that the toner mix consists of a mixture of pigmented tonerparticles and magnetizable particles, with the toner particles adheringto the magnetizable particles as a result of triboelectric effect andleaving the magnetizable particles when the toner particles are brushedin contact With the surface of the copy sheet. The toner mix is carriedas tufts on the cylinder because of the magnetic field set upsubstantially at right angles to the cylinder 17 and through the copysheet 13.

For establishing the magnetic field at right angles to the developingcylinder 17, bearing blocks 17a, 17b are made of magneticmaterial andare bridged by an elongated magnetic pole member 18 which extendsparallel to the cylinder outside a guide member 18a and with permanentmagnets 18b, 18c being provided in the circuits so that the developingcylinder is at one polarity and the cooperating pole piece at theopposite polarity. To achieve the latter, permanent magnets 18b, 18c arepolarized in parallel with one another, i.e., with the same polarity sothat the flux, indicated at 18d (FIG. 3) is distributed more or lessuniformly to the surface of the cylinder 17. The guide member 18a ismade of aluminum or other non-magnetic material so that it does notobstruct or distort the flux flowing to the cylinder. The desired levelof toner mix in the bin 16 is maintained by oppositely rotating angers19 and 2t Following brushing of the copy sheet with the toner mix bycylinder 17, the sheet is directed through the fixing unit 12 and therethe resinous portion of the toner mix is fused to the copy sheet to makethe desired permanent image on the sheet. The fixing unit 12 isexplained in detail in a copending application, Serial No. 853,123,filed Nov. 16, 1959, now Patent 3,088,386. Expeller rollers 21, 22 areprovided to pull the copy sheet through and deposit it onto a tray 23from which the finished copies can be removed.

in accordance with the present invention replenishing means are providedat the top of the developing unit for depositing measured amounts oftoner from time to time concentrated at a single position at the rear ofthe angers for immediate longitudinal distribution by the angers. Thereplenishing unit 24 is preferably mounted upon a supportingor baseplate 2-5 which forms the top plate for enclosing the toner bin andpreferably secured to a pair of side members 26, 27 of the developingunit as shown in FIG. 3. A spring-closed inspection cover 28 is providedin the plate for checking the operational level of openings 31, 32 and amounting flange 33. For'metering' toner powder from the magazine ametering disc 34 having peripheral notches '35, 36 is interposed in thecup between the stationary disc 3d and thesupporting plate 25, and adischarge opening 39 angularly offset from the ports 31, 32 of thestationary disc. Thus, rotating the disc serves to rotate a trappedquantity of toner into position for discharge.

To oscillate the metering disc 34 the disc is connected to a verticalshaft to which it is secured by a pin 41. At the lower end of the shaft4%) an arm 42 is provided having a pin 43 which engages the shaft. Thearm 42 is coupled to a solenoid 44 by a link 45, and a coil spring 46,anchored to the frame plate, which provides power for the return stroke.Outboard support for the shaft 40 is supplied by a bracket 47. Thestroke of a solenoidis preferably such that on the forward stroke, thenotch 36 of the metering disc rotates between a position under the port32 of the stationary disc to a position over the discharge port 39 inthe supporting plate. On the return stroke, the remaining notch 35performs a similar function rotating from under the port 31 to aposition over the discharge port. Thus, where both the notches 35, 36are utilized, the replenisher is capable of depositing two measureddoses of toner powder each time the solenoid is energized. In order tocut the discharge in half, one of the notches on the metering disc maysimply be omitted.

In accordance with one of the aspects of the invention the size of thedose is made adjustable by providing a choke plate secured to themagazine and above the stationary disc and having ports which may beadjusted into register with the ports in the disc. The magazine isrotatable with respect to the mounted or base plate and provided withsuitable calibrated indicia so that adjustment is effected simply byrotating the magazine. In the present instance, the choke plateindicated at 48 has openings 49, 50 which correspond to the openings 31,32 in the stationary disc. For securing the choke plate to the magazinesuitable tabs 51, 52 are provided. The magazine is made rotatable withrespect to the supporting plate by forming the base portion with anannular groove 53 engaged by lugs 54. A stationary pointer 55 cooperateswith a scale 56 which is rotatable with the magazine.

. It will be apparent, then, that when the magazine is adjustablyrotated relative movement will take place between the ports choking downthe area through which toner may enter the notches in the metering discand thereby determining the quantity of toner which is ejected duringeach operation.

For the purpose of agitating the finely divided toner and for therebypreventing packing or bridging, agitators 57, 58 are secured to theupper end of the shaft 40. The agitators are preferably spaced from oneanother as shown with the lowermost agitator being mounted more or lessdirectly over the choke plate so that it tends to sweep toner into themetering space. It is found that this construction produces a highdegree of reliability and metering accuracy even when used with tonerpowder having a particle dimension measured in terms of microns.

For the purpose of keeping the magazine 29 at a safely low temperature,a heat shield 59 is provided which is spaced from the wall of themagazine on posts 60. Windows 61 at the lower edge of the shield permitupward movement of cooling air. Thus, there is no possibility that themagazine will be heated to the point that fusion of the toner powderwill tend to take place.

In spite of the fact that the toner is deposited in a concentrated doseat one point along the length of the developing cylinder, the action ofthe transporting angers, previously mentioned, is such that the addedmaterial is immediately distributed over the width of the cylinder sothat addition of toner-does not affect copy-to-copy uniformity.

In accordance with another of the aspects of the present invention meansare provided for actuating the dispenser once for each copy made. Theactuating signal is derived from a switch 66 responsive to the leadingedge of the original and which is used in the overall control circuitrydisclosed in detail in copending application Serial No. 853,123, filedNovember 16, 1959. Referring to FIG. 2, a simple series connection 62 ismade between the switch and the solenoid 44 of the replcnisher. Sincethe replenisher may, because of its novel design, be adjusted for lowconsistent output per cycle, it is found that the toner is maintained ata desired level over long periods of time without further care orattention.

If desired, and without departing from the invention, means may beprovided for actuating the replenishing unit 24 after a predeterminednumber of copies have been processed. Thus, a timer 63 may be usedhaving input terminals 64 and output terminals 65. The timer 63 has beenindicated diagrammatically since timers are well known to those skilledin the art capable of producing an output pulse upon receipt of apredetermined, counted, number of input pulses. When using the timer theregular lead (FIG. 2) 62 is broken. The input terminals are connected tothe switch (not shown) and the output terminals are connected to thesolenoid, just as shown by the dotted lines. Thus after a predetermined,preferably adjustable, number of counts, the counter 63-triggers animpulse to the solenoid to deposit a predetermined amount of tonerpowder in the bin.

It will be seen from the above description that a replenishing unit isprovided which is easily adaptable to different electrophotographicprinting machine developing units and is economical to manufacture andeasy to maintain.

I claim as my invention:

1. In combination with a developing unit for a photocopy machine capableof developing a copy sheet having an electrostatic latent image thereon,a replenishing unit comprising, in combination, a mounting plate mountedon top of said developing unit, a toner magazine mounted on said plateand in the form of a vertical cylinder, a stationary disc spaced abovethe mounting plate, a metering disc between said stationary disc andsaid mounting plate, said stationary disc and said plate having portsangularly spaced from one another, said metering disc having notchesformed therein and having means for oscillating the disc between a firstposition in which toner is received from the port in the stationary discand a second position in which toner is discharged through said plateinto the developing unit, said oscillating means including a solenoidresponsive to development of copies so as to discharge a predeterminedquantity of toner for a preselected number of copies, and a choke platedisposed adjacent said stationary disc for adjusting the size of saidstationary disc ports to select the quantity of toner admitted to saidmetering disc notches.

2. In combination with a developing unit for a photocopy machinc capableof developing a copy sheet having an electrostatic latent image thereon,a replenishing unit comprising, in combination, a base plate, a magazineon said base plate for containing toner powder, a stationary plate insaid magazine spaced above the base plate and having first and secondspaced peripheral ports, said base plate having a discharge portarranged angularly between the ports in the stationary plate, a meteringdisc interposed between the stationary plate and the base plate, a driveshaft extending axially within the replenishing unit for oscillating themetering disc over a forward and reverse stroke, said metering dischaving first and second notches formed on the periphery thereof and soarranged that during the forward stroke toner is transported by thefirst notch from the first port to the discharge port in the base plateand so that upon the reverse stroke toner is transported from saidsecond port to said discharge port, a choke plate disposed above saidstationary plate and adjacent thereto having first and second portscoinciding with said stationary plate, first and second discharge ports,said choke plate adjustable to vary said stationary plate port sizes toselect quantity of toner discharged in each of said strokes, andagitator means secured to the upper end of said shaft for agitating thetoner above said ports.

3. In combination with a developing unit for a photocopy machine capableof developing a copy sheet having an electrostatic latent image thereon,a replenisher for toner powder in the developing unit comprising, incombination, a mounting plate having a discharge port, a magazine in theform of a vertical cylinder on said mounting plate, a shaft extendingaxially through said mounting plate and into said magazine, a meteringdisc on said shaft for metering toner through said discharge port andinto said developing unit, a choke member having a peripheral port andlocated above the metering disc, said choke member being secured to saidmagazine and said magazine being rotatable with respect to said mountingplate thereby to vary the amount of toner discharged in a cycle of themetering means, and indicia associated with the magazine for visuallyindicating the adjusted position of the latter.

4. In combination with a developing unit for a photocopy machine capableof developing a copy sheet having an electrostatic latent image thereon,a replenisher for toner powder in :the developing unit comprising, incombination, a mounting plate mounted on top of said developing unit, atoner magazine mounted on said plate and in the form of a verticalcylinder, a stationary plate in said magazine spaced above the mountingplate and having first and second spaced peripheral ports, said mountingplate having a discharge port arranged angularly between the ports inthe stationary plate, a'metering disc interposed between the stationaryplate and the mounting plate, a drive shaft extending axially within thereplenishing unit for oscillating the metering disc over a forward andreverse stroke, said metering disc having first and second notchesformed on the periphery thereof and so arranged that during the forwardstroke toner is transported by the first notch from the first port tothe discharge port in the mounting plate and so that upon the reversestroke toner is transported from said second port to said dischargeport, a choke member being secured to said magazine and said magazinebeing rotatable with respect to said mounting plate thereby to vary theamount of toner discharged in a cycle of the metering means, andagitator means secured to the upper end of said shaft for agitating thetoner above said ports.

References Cited by the Examiner UNITED STATES PATENTS 2,446,582 8/48Gopner 222-362 X 2,944,707 7/60 Steinmetz 222-663 X 3,088,386 5/63Sugarman --1.7

WILLIAM D. MARTIN, Primary Examiner. V

1. IN COMBINATION WITH A DEVELOPING UNIT FOR A PHOTOCOPY MACHINE CAPABLEOF DEVELOPING A COPY SHEET HAVING AN ELECTROSTATIC LATENT IMAGE THEREON,A REPLENISHING UNIT COMPRISING, IN COMBINATION, A MOUNTING PLATE MOUNTEDON TOP OF SAID DEVELOPING UNIT, A TONER MAGAZINE MOUNTED ON SAID PLATEAND IN THE FORM OF A VERTICAL CYLINDER, A STATIONARY DISC SPACED ABOVETHE MOUNTING PLATE, A METERING DISC BETWEEN SAID STATIONARY DISC ANDSAID MOUNTING PLATE, SAID STATIONARY DISC AND SAID PLATE HAVING PORTSANGULARLY SPACED FROM ONE ANOTHER, SAID METERING DISC HAVING NOTCHESFORMED THEREIN AND HAVING MEANS FOR OSCILLATING THE DISC BETWEEN A FIRSTPOSITION IN WHICH TONER IS RECEIVED FROM THE PORT IN THE STATIONARY DISCAND A SECOND POSITION IN WHICH TONER IS DISCHARGE THROUGH SAID